1. Field of the Invention
The present invention relates generally to a pad conditioning tool for Chemical Mechanical Polishing (CMP) process, and more particularly a pad conditioning tool that has a plurality of sapphire dressing particles for dressing a wafer polishing pad such that the wafer polishing pad possesses high efficient polishing yield.
2. The Prior Arts
Rapid advance of semiconductor product and optical instrument demands minimizing width of circuit paths in the integrated circuit board. The more the circuits are integrated into a chip, the more planarization of surfaces in the semiconductor material is required, since formation of a circuit or thin film is obtained only after each deposition process. To be more specific, if the integrated circuit includes 10 conductive layers (like Cu, Al, W), insulated layers (like black diamond) and anti-abrasive layer, several deposition processes are conducted so as to form the 10 conductive layers. Since smoothing of the surface is required after formation of each layer, presently Chemical Mechanical Polishing (CMP) technique is generally applied in the production of a semiconductor, which in fact is a process of smoothing surfaces of silicone wafers or other base material with the combination of chemical and mechanical forces, so that it is named CMP. The CMP technique generally includes two parts, namely, (I) polishing the semiconductor surface with a polishing pad; and (II) conditioning the polishing pad to provide effective polishing ability. FIG. 1 illustrates a conventional pad conditioning tool, which conducts conditioning of the polishing pad 3 while the polishing pad 3 conducts polishing operation on a wafer simultaneously without the need of stopping the operation. As shown, a rotary device 5 is mounted at each back of the conventional pad conditioning tool 2 and the wafer 1 so as to cause the former to rotate relative to the polishing pad 3.
The conventional pad conditioning tool generally includes a plurality of diamond particles formed on a metal substrate via hard brazing process. Because the diamond particles protrude outwardly from the outer surface at different heights, the exterior appearance and dimension or height is not uniform so that the diamond conditioning tool can only provide roughly about 40% polishing effect. Note that thousands of diamond particles are electroplated or via hard brazing process onto the metal substrate so that there exists co-relation between the surface areas and the number of diamond particles mounted within the surface area and the diamond particles at the adjoining surfaces may fall off owing to contraction and expansion of the metal substrate at different temperatures. The diamond particles may fall off upon introduction of the slurry and the etching process on the metal substrate or the tips of the diamond particles break off owing to non-uniform strength, which, in turn, may result in scratches partially or wholly on the wafer being polished. Of late, a pad conditioning tool has been developed, which includes an integrally formed polishing pad made from relatively hard sapphire material and which are exposed to an exterior more evenly and thus provides longer service life and efficient polishing rate. However, the polishing surface of the polishing pad conditioned by the above-mentioned pad conditioning tool still suffers a new cilia and trench error of 10˜20 μm, which needs to be overcome.